1. Field of the Invention
This invention relates to a navigation system for a hierarchy tree. More particularly, the invention relates to display management of and selective presentation of tree levels and tree branches in the hierarchy tree of an information system.
2. Description of the Related Art
The use of tree formats to display an object hierarchy in a computing system is quite well known. These trees typically follow a text outline format, and the outline is oriented vertically with each level of a branch positioned vertically lower and to the right on the display screen than the previous level of the branch. Thus, the tree grows from upper left to lower right on the display screen. Because of this format, the upper right portion of the display screen is wasted area, and never used to map the hierarchy being displayed.
In the known tree navigation system, objects at an outer branch level (further out on a branch) are displayed by clicking on the next inner level object. Accordingly, to move out a branch, the user must mouse click on each object along the branch to open the next outer level of the branch. For example, in Windows Explorer in the Microsoft Windows 95 program, the user must mouse click on each node of the tree to open the next branch level of the tree. Finally, the last level of the tree is displayed as objects in a folder of the previous branch level.
It is also well known to select drop down menus in a windowing system. A menu is opened by clicking on the menu name. Thereafter, an object in the menu that points to another menu will automatically open the next menu if the mouse cursor is placed on the object. Only objects pointing to further menus will open in this way, and only one menu at a next menu level may be opened at any one time.
A hierarchy navigation system is needed that has the capability to open multiple branches and display the multiple branches simultaneously. Further, a tree navigation system is needed that has the capability to explode multiple levels along a branch in one operation. Also, a tree navigation system is needed that rapidly opens branches to objects from which actions may be launched, and provides for controlled closure of selected branches.